Venusian view eludes scientists

Astronomers planning to peer beneath Venus' thick sulfuric acid clouds are disappointed to find a leaky infrared-camera filter will keep them from realizing their goals. The innovative approach would have combined adaptive optics and daytime observations using the Dunn Solar Telescope in Sunspot, New Mexico.

Cloud formations on Venus are especially visible on the planet's nightside. Planetary scientist Nancy Chanover observed Venus in 2004 from the Apache Point Observatory in Sunspot, New Mexico.

Nancy Chanover, NMSU

Much to the chagrin of planetary scientist Nancy Chanover of New Mexico State University and colleague Eliot Young of the Southwest Research Institute, instrument problems have dashed their observing plans for now. "The filter on our infrared camera is leaking thermal radiation and keeping us from observing the planet," says Chanover. Excess heat from the leaky filter is reaching the detector, making observations impossible.

Although brilliant enough at times to be mistaken for a plane's landing light, Venus is difficult to observe for two reasons: Its proximity to the Sun means there is little time for night observations before the Sun rises or the planet sets; and when it is easily visible, it sits close to the horizon, where an observer must also peer through the majority of Earth's atmosphere.

The planet can be seen on either the eastern horizon an hour or two before dawn, or on the western horizon just after sunset. Daytime observations would allow astronomers to track features for up to six hours at a time.

Venus' surface features cannot be seen in optical wavelengths (350-750 nm) with ground-based telescopes because of the planet's thick sulfuric acid clouds floating 30 to 40 miles (48 to 64 km) above its surface. However, observations in the infrared (2,300 nm) coupled with the Dunn telescope's adaptive optics should give scientists better data about venusian weather.

Unfortunately, we'll have to wait until the infrared camera's filter problems are resolved. The researchers say no immediate work-around of the problem is forthcoming, and no date has been set for further observations.